Trying to pay on a delivery app and it says you need a 'Korean phone number' to sign up? Banks and government sites often block you too, saying you must verify your identity once by SMS with a Korean number. The reason is simple. In Korea, with the rapid development of internet and mobile services, a culture of verifying identity by text/call took hold, and carriers check identity at signup and assign numbers. This process helps reduce fraud and duplicate accounts. ## How did this happen? As smartphones and apps have become central to daily life, many companies use text messages for sign-up and payment verification. Mobile carriers also check subscribers' real names and manage phone numbers accordingly. So, verification may not work with foreign numbers or anonymous temporary numbers, or there may be restrictions. ## Legal and ready-to-use methods - Short stays: buy a tourist SIM (SIM card) at airport convenience stores or carrier booths, or use roaming from your home carrier. Before buying, check which verifications it can be used for. - Long-term stays (students, workers, etc.): At a carrier branch (SK/KT/LG U+ etc.) or a low-cost carrier/MVNO shop, show your passport and alien registration card (or a valid visa) and they will activate a SIM for you. Prices and required documents vary by store, so check on-site. - School assistance: Many university international offices can help with SIM sign-up or recommend services. Caution: Temporary online number services or illegal brokers may be blocked during bank or public-service verifications or risk account suspension, so avoid them.